Recent content by Rahmuss

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    Direction of Magnetic Field for a Charged Rotating Disc

    waht - Thanks. And that part I understand just fine. There is only a z-component of the electric field, so when I do a cross product, I get both an r-component and a theta-component. gabbagabbahey - So the way you're describing it, the magnetic field seems to come up at the center of the...
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    Direction of Magnetic Field for a Charged Rotating Disc

    Homework Statement The question actually asks for the equation for the magnetic field for the rotating disc; but all I'm after is the direction of the magnetic field. Homework Equations None were given; but I've been using: \nabla \times \vec{E} = -\frac{\partial \vec{B}}{\partial t}...
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    Electron Spin State and Values

    Ah... Ok. Great! Thanks 2Tesla. That helps a lot. That makes sense now. Ok, I can see why I wasn't getting it. Thanks again.
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    Electron Spin State and Values

    Ok, I have from my teacher that A = \frac{1}{3}, and that \left\langle S_{x}\right\rangle = \frac{2\hbar}{9}. I can normalize it and get A = \frac{1}{3}; but I can't get the correct expectation value. Here is what I am doing: \left\langle X | S_{x}X\right\rangle = A^{2}\frac{h}{2}[(1+2i)...
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    Electron Spin State and Values

    Any thoughts on normalizing this? I tried another way and got \frac{1}{3} and another way and I got \frac{16\hbar - 2\hbar i}{18}. And neither of those seem to work. I thought that 1/3 would work; but when I try to find the expectation value I get \frac{\hbar}{2} \frac{13}{3}.
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    Eigenvalues and Eigenspinors: How to find them for the S_y matrix?

    Oh, ok. Great, that's exactly what I needed. Thanks Count Iblis and nrqed and others.
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    Eigenvalues and Eigenspinors: How to find them for the S_y matrix?

    I'm just not sure how to get from my relation: a = \mp ib to: X^{y}_{+} = \frac{1}{\sqrt{2}}\begin{pmatrix}1 \\ i \end{pmatrix} X^{y}_{-} = \frac{1}{\sqrt{2}}\begin{pmatrix}1 \\ -i \end{pmatrix}
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    Eigenvalues and Eigenspinors: How to find them for the S_y matrix?

    Well, after a few days I'm still a bit confused with this problem. According to wikipedia the eigenspinors of S_{y} are: X^{y}_{+} = \frac{1}{sqrt{2}}\left[ \begin{pmatrix}1 \\ i \end{pmatrix}\right] X^{y}_{-} = \frac{1}{sqrt{2}}\left[ \begin{pmatrix}1 \\ -i \end{pmatrix}\right]...
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    Electron Spin State and Values

    [SOLVED] Electron Spin State and Values Homework Statement An electron is in the spin state: X = A\begin{pmatrix} 1-2i \\ 2 \end{pmatrix} (a) Determine the constant A by normalizing X (b) If you measured S_{z} on this electron, what values could you get, and what is the probability...
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    Expectation Values of Spin Operators

    Oh, you're right, it's just S_{x}, not S_{x}^{2}. Thanks. And I'll change the vectors (on my homework); but is the rest correct then?
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    Expectation Values of Spin Operators

    [SOLVED] Expectation Values of Spin Operators Homework Statement b) Find the expectation values of S_{x}, S_{y}, and S_{z} Homework Equations From part a) X = A \begin{pmatrix}3i \\ 4 \end{pmatrix} Which was found to be: A = \frac{1}{5} S_{x} = \begin{pmatrix}0 & 1 \\ 1 & 0...
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    Sping Matrices and Commutation Relations

    Err... hey, you're right. :D This idiot thanks you.
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    Sping Matrices and Commutation Relations

    Homework Statement Check that the spin matrices (Equations 4.145 and 4.147) obey the fundamental commutation relations for angular momentum, Equation 4.134.Homework Equations Eq. 4.147a --> S_{x} = \frac{\hbar}{2}\begin{pmatrix}0 & 1 \\ 1 & 0 \end{pmatrix} Eq. 4.147b --> S_{y} =...
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    Eigenvalues and Eigenspinors: How to find them for the S_y matrix?

    Count Iblis - I understand what you mean. And that makes perfect sense too, that's a great way of getting the different spins. So wikipedia shows the S_{y} e-spinors as something different. They show: S_{y}: X^{y}_{+} = \frac{1}{\sqrt{2}} \left[ \begin{array}{cc}1 \\i...
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    Eigenvalues and Eigenspinors: How to find them for the S_y matrix?

    nrqed - Right! Yeah, I didn't mean for my example of finding the eigenvalues as the problem that I was trying to solve. So... \begin{pmatrix}-\lambda -i\frac{\hbar}{2} \\i\frac{\hbar}{2} -\lambda \end{pmatrix} = 0 \lambda^{2} =\frac{\hbar^{2}}{4} ---> \lambda = \pm \frac{\hbar}{2}...
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